Well, I cannot really speak from experience on this one, as the feature is still in Private Preview, so I will simply leave it to Ross Adams:
If you are interested in Identity management for Office 365, this is the session to watch from Ignite. Do watch from the start as well, to learn about support for LDAP sync, soft-match on UPN, the new “soft” handling of duplicate attributes, the 500 proxyaddresses issue and more 🙂